Respirators which chemically regenerate the oxygen content of exhaled air are known to the art. For example, such apparatus are generally disclosed by U.S. Pat. Nos. 4,019,507 (Oetjen et. al.), 3,980,081 (Cotabish et.al.), 2,403,991 (Murphy et.al), 2,403,981 (Jackson et.al.), British Specification No. 488,666 (Regnault) and Russian Specification No. 234,870.
However, none of these references teach or suggest a regenerative respirator which advantageously provides a simple structure which utilizes a single element to simultaneously provide means for supporting a chemical regenerative agent, means for providing ready access to such chemical agent for rapid replacement thereof, and means for directing the flow of regenerated air through the respirator.
Our new invention advantageously utilizes a simple container to simultaneously support a chemical regenerative cartridge, to provide ready access to the cartridge housed therein, and to form a channel with the outer surface of the cartridge itself for directing the flow of regenerated air, thus eliminating the need to provide separate means (i.e. additional pipes or tubes) to perform this function.
A brief discussion of each of the aforementioned prior art references readily demonstrates the novelty and unobviousness of our inventive concept.
(1) The Oetjen apparatus is not a regenerative respirator. It comprises a pure source of oxygen which is released into the respirator. Exhaled air is discarded, not regenerated.
Oetjen is devoid of teaching of means for rapid and easy replacement of the oxygen cartridge.
(2) Although Cotabish recognized the problem that the components of portable respirators are of such small size that they can only sustain life for a very limited time, its proposed solution teaches against our new invention.
Cotabish provides a respirator which can be connected to a large supplemental oxygen regenerative unit after the initial regenerative chemical has become spent.
In contrast, our new invention accomplishes the same result in a more convenient way because it enables the user to easily and rapidly replace a small regenerative cartridge with a fresh one. The cartridges are small and several of them can be easily carried by the user. By successively replacing cartridges, breathing can be sustained for extended time periods.
(3) Russian Specification No. 234,870 does not suggest a respirator having an easily replaceable cartridge, nor the utilization of the structure of such cartridge to form a passageway for directing the flow of air.
(4) Although the Jackson patent discloses a respirator with a removable canister, it is evident from its disclosure that the removal and replacement of such canister requires some involved and complex operations.
Jackson does not use a single breathing tube for both inhaling and exhaling but requires a separate tube for each operation. Also, Jackson does not pass exhaled gas directly to the regenerative agent, but releases the gas beyond the agent. The gas rises and only then comes into contact with the regenerative agent.
Since Jackson does not disclose a container for housing the regenerative agent, it cannot teach or suggest the use of a channel between a chemical cartridge and an associated container for directing the flow of air through the respirator.
(5) The Murphy patent also discloses a removable canister. However, the Murphy apparatus provides means (including valves and tubes) for causing the regenerated air to bypass the canister during the inhalation cycle. This necessarily complicates the operations involved in replacing the canister.
Murphy teaches against our inventive concept, which passes air through the regenerative agent during both the inhalation and exhalation cycles. We have eliminated the need to provide means for bypassing the regenerative cartridge, and thus have simplified the procedure for replacing the cartridge.
It appears from the Murphy drawings that the lid of the canister container can only be opened about 45.degree.. This complicates the changing of the canister since a replacement canister cannot be directly inserted but must be angled into position. In our invention, the lower portion of a container housing the chemical cartridge can be completely removed, thus providing unobstructed access.
Furthermore, Murphy does not teach or suggest the use of a channel formed by the container and canister for directing airflow within the respirator.
(6) The British Specification is directed towards a respirator which is capable of passing pre-determined portions of exhaled air through different chemical agents. It is also primarily concerned with means for cooling the respirator.
It does not teach the use of a channel between the chemical cartridge and container for directing the flow of air. In fact, it does not show any channel linking the cartridge to a storage bag.
The free space between the bottom of the cartridge and its associated container is not used to channel the flow of regenerated air directly to storage means. The air within this open space must be re-passed through the cartridge itself before flowing to the storage means because there is no direct channel passage means provided thereto from this open space.
In contrast, our invention provides direct channel means between the cartridge and storage means. Our channel is formed between the cartridge itself and its associated container, simplifying the overall structure of our respirator.
To summarize, none of the aforementioned prior art shows or suggests our new apparatus which will now be described in greater detail.